If defects such as foreign substances or flaws are present on a mirror-like surface of a wafer used in semiconductor-manufacturing processes, the defects affect a production yield of the semiconductor devices. It is therefore vital to inspect the defects on the mirror-like wafer surface. Additionally, management standards relating to the defects are required to be raised to higher levels with the progress of the semiconductor device manufacturing processes. Surface inspection apparatuses are used for such defect management. Known surface inspection apparatuses detect defects on the surface of an object to be inspected, by irradiating the surface of the object with a beam of light such as laser light and detecting the light reflected or scattered from the surface.
Examples of surface inspection apparatuses are described below. The surface inspection apparatus described in Patent Document 1 listed below includes a plurality of detectors each different in elevation angle in addition to azimuthal angle, and is constructed so that the selection of a detector receiving the strong light scattered from foreign substances and/or defects enables background-scattered light to be suppressed for enhanced detection sensitivity for foreign substances and defects.
Although not intended for wafers with a mirror-like surface, surface inspection apparatuses for wafers with circuit patterns formed thereupon include one described in Patent Document 2 listed below. Surface inspection apparatuses for other semiconductor substrates include ones described in Patent Documents 3 to 8 listed below.